Patent GB-772577-A (GB)
Title: Telegraph transmitter
IPC: H04L17/12
Filed: 1955-06-10
Abstract: 772,577. Telegraph transmitters. CREED & CO., Ltd. June 10, 1955 [June 16, 1954], No. 16813/55. Class 40 (3). A telegraph transmitter, in which signals to be transmitted are stored on a medium which is advanced in a predetermined direction past sensing means, comprises an arrangement by which a loop is formed in the medium during its advancement past the sensing means and a part of the loop can be transferred to a position opposite the sensing means so that signals stored in the loop portion can be repeated. The perforations in the tape 16 are sensed by feeler pins 14a carried by feeler levers 14 operated by a magnet 13 which also operates a lever to step the sprocket feedwheel 18. A lid 26 having a window 27 and a latch 28 is mounted above a guide-plate 31, Figs. 5, 6, carried by the transmitter and carries two bars 32 having projections 33 on which is slidably mounted a slide 34 having downwardly projecting portions forming six channels 36. The slide 34 has an extension 38 with a hole 39 which is engaged by a pin 40 on a rack 41 when the lid 26 is in its closed position. A tape-hold magnet 43 operates an armature 46, manually held in its retracted position by a spring 51 and carrying a pin 49 guided in a sleeve 52 and arranged to engage a feed-hole 16a in the tape 16 when the magnet is energized. A pinion 53 rotated by a motor M energized at the beginning of a message moves the rack 41 to the left and takes with it the slide 34 so that the tape 16 after passing the sensing pins 14a forms a loop 16b containing the initial characters of the message. The limiting positions of the rack 41 are determined by stops 57, 58 and the channels 36 allow the slide 34 to move over the feeler pins 14a and the pin 49 which arrests the tape 16 to form the loop 16b. When the rack is in its right-hand position contacts 63, Fig. 9, are closed and contacts 64 are open and stepping impulses from an interrupter 68 operate the tape stepping magnet 13 over contacts 71 of a relay 73 which is de-energized if current flows through both its windings. At the commencement of a message, a relay 78, operated manually, or automatically, by a predetermined signal group, energizes a relay 79 closing an operating circuit for the motor M which moves the rack 41 to the left. Contacts 63 open and allow relay 73 to operate and lock up over its contact 72 so that the circuit of the stepping magnet 13 is broken. The closure of contacts 64 energizes the tape-hold magnet 43 which actuates pin 49 to hold the tape 16. When the rack 41 reaches its left-hand position contacts 62 close and complete a circuit for the left hand winding of relay 73 which releases and allows the pulses from the interrupter 68 to actuate the magnet 13 to step the tape so that signals are transmitted and the loop 16b is formed. When the initial part of the message has been transmitted relay 78 is released, e.g. by a predetermined combination of characters. The circuit of relay 79 is broken and relay 76 is operated. The release of relay 79 cuts off the motor M and allows the interrupter 68 to energize relay 73, breaking the circuit of magnet 13 to interrupt the stepping of the tape. The spring 54 returns the rack 41 to the right-hand position in which projection 59 opens contacts 64 so that the magnet 43 releases and its armature 46 withdraws the stop-pin 47, and contacts 63 close so that over operated contacts of relay 76 the relay has its left-hand winding energized and falls off so that the initial portion of the loop 16b is again presented to the sensing pins 14a and the signals contained in the loop portion 16b of the tape are retransmitted. Relay 66 can be energized when the tape is exhausted or broken to open the circuit of the magnet 13 which effects the stopping of the tape.